Originally raised as a plant health issue of potential concern, the health of Alder trees in Scotland was initially investigated in project PHC2019/09: Health status of Alder in Scotland. This preliminary study found that there could be a legitimate concern over Alder that may have complex causes (several biotic and abiotic stresses were noted), and the timeline of these health issues (gradual or rapid) was unclear. Further scoping and examination of the problem by established experts was recommended, leading to this project. The project will conduct:
• Expert visitation of sites to seek evidence of problems with alder health, gain some understanding as to possible causes, and identify key dimensions of a thorough study should this prove warranted. Lab work to confirm field diagnoses.
• Preliminary citizen science request inviting site-specific records of concern over alder health (potentially via the trained Observatree volunteer network to gather data), with analysis to identify any geographic clustering.
• Produce recommendations for further work including; refined survey methodologies for widespread application by interested organisations; identification of potential candidate sites for detailed study over time, and; a discussion document on risks to existing alder of expansion of riparian woodland.

Concerns over the condition of alder in the north of Scotland were raised in 2019 and PHC compiled a project call to determine the cause, scale and consequences of the potential progressive Alder decline. This project was put on hold over winter 2019 and was due to commence at the start of May 2020 when the season was conducive for field sampling, however, due to continuing COVID restrictions, no site visits were possible.

Therefore, a small desk study was undertaken by Forest Research to provide a firmer evidence base and begin to identify the nature and scale of alder health problems in Scotland. A request to Scottish Forestry’s Tree Health team for information of sites at which alders are currently displaying symptoms of poor health identified 15 sites. The symptoms displayed at these sites differed widely and are a strong indication of different agents being associated with the decline of alders at different sites. Collation of the data for these sites is now complete and provides a firm basis upon which to carry out targeted field visits when fieldwork becomes feasible. Discussions are underway between experts at FR, RBGE, Hutton, and NatureScot to consider options for fulfilling the objectives of the original project call.